Switches and mechanism for forming chords in electronic musical instruments



March 11, 1969 P. s. SOPRANI 34323635 SWITCHES AND MECHANLSM FOR FORMING CHORDS IN ELECTRONIC MUSICAL INSTRUMENTS Filed April 2'7, 1965 $heet of 2 A O 2 f0 8 O a a a a o 7 a; a 1 7 S f/ a r M i... 5

INVENTOR ATTORNEYS March 11. 1969 P. s. SOPRANI SWITCHES AND MECHANISM FOR FORMING CHORDS IN ELECTRONIC MUSICAL INSTRUMENTS Filed April 27, 1965 Z of 2 Sheet ll E R H INVENTOR P 01.0 ETT/M/d SOP M ATTORNEYS United States Patent() US. Cl. 200-166 Int. Cl. H01h 13/76 4 Claims ABSTRACT OF THE DISCLOSURE A chord-selecting device for electronic musical instruments comprising a keyboard or button-board for (bass) note and chord control buttons, parallel metal springs positioned to be selectively deflected by the buttons to close electric circuits carrying diiferent audio frequencies,

and common conductors positioned transversely of the springs to be contacted selectively by the springs that are deflected.

This invention relates to a novel structure of the mechanical members used for a contemporaneous picking up of a plurality of frequencies intended to form musical chords and accompaniment combinations adopted in various electronic musical instruments.

More particularly, the present invention hereinafter described permits a plurality of previously selected frequencies to be resounded, such frequencies being intended to form a musical chord by passing only a key, a botton, a pushbutton or a control of any kind.

In previously employed systems (such as the left hand mechanism of a conventional accordion), selection and frequency coupling was effected by a multiple lever system whereas the present invention obtains the same result by a simplified mechanical device controlling electric circuits so that the number of moving parts can be minimized. Such an arrangement permits the dimensions to be reduced, eliminates adjustment problems and excludes all extraneous noises produced by articulated joints.

These and other advantages and features of the present invention will be more apparent from the following description which is to be considered in conjunction with the accompanying drawings in {which like reference characters refer to like parts.

-The device of the present invention is shown by way of example and not by way of limitation in an embodiment in the accompanying drawings in which:

FIGURE 1 is a sectional view of the device comprising the present invention,

FIGURE 2 is a perspective view of the same device and FIGURE 3 is a further perspective view of a portion of the contact spring bearing plate for picking up the frequencies, the base plan being swung forwards in order to show the underside of it.

Particularly referring to FIGURES 1 and 2, the electromechanical system includes buttons 1 and 1', formed of plastic material and shaped to. provide a limit stop upon pressing. Such buttons are slidable in guides 2 and 3 and carry along their shanks helical springs 4 urging each button outwardly, whereas at the shank ends plastic connecting plates 5 and 6 are attached, said connecting plates acting as guides for long contact springs 7 and 8 when buttons 1 or 1 are depressed to bring'the springs into contact with bars 9 or 10 mounted on stationary supports Application of plastic connecting plates 5-6 on button shanks 1 and 1' is effected by pressure and glue. Each 3,432,635 Patented Mar. 11, 1969 bass note button" 1 guides only one ;of the contact,

thereof is unlimited, but in practice triple contacts have been selected for normal chord requirements and thear .rangement of springs 8 with related frequencies coupled to such springs is shown in FIGURE 3.

It will now be apparent that on depressinga bass. button 1,,said button with its fork-shaped connecting plate 5 will cause the corresponding spring 7 anchored to the contact plate 11 to be moved, the spring then contacting conduct bar 9 which is common to all the bass springs.

Vice versa, on depressing a chord button 1', this will drag into motion those springs 8, which are withinthe bracket shaped connecting plate 6 of the depressed button and H will bring them into contact with conducting bar 10, such a bar being common for all sets of chord forming springs 8.

In FIGURES 1 and 2 it is seen that bass contact springs 7 are secured at one end to contact plate 11 but are free at their other ends, whereas chord-forming contact springs 8 are guided at their other ends as at 12.

It is a further object of the present invention to provide a practical embodiment of contact plate 11 whereby various frequencies can be applied to the contact springs.

Such springs 7 and 8 are arranged in two rows, A and B respectively, on an insulating plate 11, row A serving as bass contact springs 7 i and row B as chord contact springs 8, plate 11 having on either side of it and parallel to rows of contact springs 7 and 8 twelve conducting lines for basses and twelve con-ducting lines for chords, all of them being insulated from one another and at one end being connected by conductors 13 to the required frequency generators (not shown).

Itlis thus apparent that delivery of a preselected frequency to a given contact spring 8 can be effected by providing a conducting strip 16 between point 17 where spring 8 is connected to plate 11 and the conducting line 18 carrying the required frequency.

Both the conductive lines 18 and the strips 16 can be advantageously formed as parts of a doubled printed circuit as shown in FIGURE 3, thereby eliminating the connecting operations between the springs and the frequency conducting lines by the application of simple rivets 14 (FIGURE 3), said rivets being inserted at predetermined points for connecting printed connections to the springs on one side of the plate to the conducting lines on the other side.

The system herein described can be used in electronic musical instruments also in order to create combined sounds, which are different from conventional chords intended for accompaniment.

What is claimed is:

1. A mechanical device for simultaneously picking up a plurality of frequencies produced by electronic circuits, including a button-board with slidably mounted pushbuttons similar to that which is conventionally used on accordions for accompaniment to be left-hand performed, said device comprising a plurality of variousifrequency carrying springs anchored at one end to a contact plate, a common conductor extending transversely of the springs to pick up frequencies carried by said springs, forked plates attached to the inner ends of said keys and arranged to act selectively on said springs so that pressure exerted on one of the keys causes contact of the preselected carries a printed circuit on one side of it to conduct the various frequencies to their respective springs.

3. A mechanical device for picking up singly or simultaneously one or more audio frequencies produced by electronic circuits, including a conventional keyboard for musical instruments with keys of known shape or a button-board with pushbuttons mounted on a slide guide, similar to the one that is conventionally used on accordions for accompaniment; this new device including a given quantity of thin contact helicoidal row arranged springs and attached on one side only by means of metal tubular eyelet rivets inserted in an insulating bearing plate I having printed circuits on both sides, With parallel and convergent'conductors which, through thevabove-mentioned rivets, carry the different audio frequencies to said loose contact helicoidal springs, which are activated by the keys or buttons but are not fixed to the single keys and buttons, since these springs can be engaged by more than one key or button by means of a single push insulating forked plate attached to the inner ends of these keys and buttons, and arranged in order to act selectively on said springs so that the hand pressure exerted on one of the keys or buttons causes the contact of these preselected springs, which are pushed b the forked plate, against a common conductor which extends transversely of the springs in order to pick up the note and form the desired chord.

4. The device of claim 3 in which the plate bearing the contact springs has been carried out by means of a circuit printed on both sides of the same plate which is especially made out to obtain parallel convergent connections to conduct the different frequencies to their respective springs; I

References Cited UNITED STATES PATENTS 2,630,503 3/1953 Larsen et a1. 2,816,181 12/1957 Mann et a1. 3,068,334 12/1962 Gibbs et al. 200166.1

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner. 

